1. Technical Field
The present invention relates to a unit and a method each for controlling an electromagnetic relay which opens and closes a contact point by applying an electric current to an exciting coil.
2. Related Art
Conventionally, there has been known a unit for controlling an electromagnetic relay which unit turns on an electromagnetic relay by supplying rated power to the electromagnetic relay and then, in order to maintain an on-state of the electromagnetic relay, controls a voltage, applied to an exciting coil, to be equal to or lower than an operating voltage and equal to or higher than a return voltage (Patent Literature 1).
The unit is a relay drive circuit which turns on an electromagnetic relay by applying, to an exciting coil, a voltage equal to or higher than an operating voltage by use of a collector current with which a semiconductor switching element has been turned on. The unit is configured so as to, after turning on the electromagnetic relay, control the voltage, applied to the exciting coil, to be equal to or lower than the operating voltage and equal to or higher than a return voltage, in order to keep the electromagnetic relay turned on.
The unit thus configured is capable of suppressing electric power consumption while keeping an electromagnetic relay turned on after turning the electromagnetic relay on.